The conventional circuit breaker uses a fuse between the switch and the circuit so that when there is electrical overload, the fuse will first melt before the overload causes damages. However, if the fuse is not properly installed or an improper fuse is used, the overload current cannot melt the fuse and may result in a disaster. U.S. Pat. Nos. 5,262,748, 4,167,720, 4,937,548, 5,223,813, 5,451,729, and 5,558,211 disclose different types of circuit breakers which commonly include a complicated mechanism to drive the bimetallic plate which is expected to be deformed and bent when there is current overload. Nevertheless, it is noted that the bimetallic plate may not be completely deformed as desired because it is not possible to be freely deformed, and the bimetallic plate is still in contact with the terminal so that sparks may be generated and therefore cause disaster.
Therefore, it is desired to have a protection mechanism for a switch device wherein a pivotable push member pushes the bimetallic plate downward to set the switch device in an “ON” status and the push member is pivoted away form the bimetallic plate to allow the bimetallic plato to be completely deformed when there is current overload.